If you've watched Stephen King's "It," you may find yourself with a new, unhealthy fear of clowns (coulrophobia) -- and you're not alone. While there are no statistics on some of the stranger phobias, such as how many people suffer from the fear of clowns, an estimated 19.2 million American adults suffer from specific phobias [source: National Institute of Mental Health]. That's about 9 percent of Americans ages 18 and older.

Phobias are exaggerated, irrational fears, and they're considered a type of anxiety disorder. There are three categories of phobias: agoraphobia, social phobia and specific phobias. Agoraphobia is the fear of not being able to escape easily from a place or event, and people who suffer from this phobia most often avoid open and public spaces. Social phobias cause people to have irrational fear of being around other people and social situations.

Then there are specific phobias, which occur when a person is irrationally afraid of a place, object or situation, such as the fear of flying (aviophobia) or the fear of public speaking (glossophobia). Specific phobias are broken into five different types:

Animal phobias

Natural environment phobias

Blood-injection-injury phobias

Situational phobias

Other phobias that don't fit the above categories

These phobias often develop when we're kids and are thought to be caused by traumatic events, brain chemistry and learned behaviors from our parents.

Specific phobias can range from something common, like a fear of heights (acrophobia), to the more obscure, such as an excessive fear of the color purple (porphyrophobia) or of beards (pogonophobia). While people suffer from a countless number of phobias -- imagine you could develop intense fear of almost any situation or object -- we've collected 10 of the strangest ones out there. First up, let's talk about the irrational fear of paper.